bkanxer: the stone reefs of brazil. 149 



North of Rio Caniaragibe (S. lat. 9° 19') in the State of Alagoas, at 

 a place known as Marceneiro, the following section is exposed on the 

 beach. 



Coral reef 



TTTnTrTTTrTTTT)Yf^-^^ - 



Fig. 82. Section at Marceneiro. 



This calcareous rock rises about 2.3 to 2.6 metres above low water, 

 while the total height of the bank amounts to 3.2 metres above low 

 tide. 



Elevated beaches, State of Bahia. — In 1879 Eichard Rathbun, for- 

 merly member of the Commissao Geologica do Brazil, now of the Smith- 

 sonian Institution, published an article on the stone reefs, in which he 

 gives a brief description of an elevated beach at Porto Santo, on the 

 island of Itaparica, bay of Bahia.^ This description is so important that 

 it is given at some length : " At Porto Santo, there is a curious 

 example of consolidated beach structure, the only instance of the ele- 

 vation of such material of which we are aware. At this place we find 

 a cliff back of the beach, having a length of about 1,100 feet, and a 

 greatest height of about thirteen feet, and composed almost entirely of 

 sand and gravel, cemented by lime into a sandstone. Tlie lower part 

 of the cliff is very hard in texture, and contains numerous fragments of 

 corals and shells, the latter being frequently found entire. Many of 

 the species of both exist in abundance throughout the bay. The upper 

 part of the cliff is of almost pure sand, and has been so incompletelv 

 hardened as to crumble readily between the fingers. The amount of 

 calcai-eous material in the lower portion is very great, and it is said to 

 yield a good quality of lime on burning. 



"Whether this cliff belongs to the same class of structures as the reefs 

 or not, it is, at least, composed of the same materials, and must have 

 been formed in about the same way. Its present elevated position — 



1 American Naturalist, Juno, 1879, XIII. 347-358. A somewhat longer article 

 on this same deposit was published b}- Mr. Rathbun, entitled A praia consolidada e 

 suhlivada e os samhaqut's de Porto Santo. Archivos do Museu Nacional do Rio dc 

 Janeiro, 1878. III., p. 172-4. 



